NAP-140 Clone Amp Kit on Ebay - Page 63 - diyAudio
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Old 15th March 2011, 09:32 PM   #621
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Join Date: Sep 2005
Hello
Avondale wrote max 50V rail at 8 Ohms.
I tried 39-0-39V transformer to me didn't work. It was very unstable.
The Avondale kit much better than the Ebay kit.
I have a set Ebay kit $20 if someone need it.
Actually I tested at lest 4 different type of design.
The next I want to test with the same transistors what Chrome bumper use.
These amplifier is very sensitive even if you change a PC of wire! If you want good sound you have to spend a lot of time , to test different parts, wires etc.

Greetings
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Old 15th March 2011, 09:36 PM   #622
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I do not know Gigawork kit.
I purchased my kit from Tubeshunter , all transistors were orig.
Greetings
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Old 16th March 2011, 12:43 AM   #623
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Quote:
Originally Posted by gaborbela View Post
Hello
Please not be fooled by the look of the amplifier !
Those are Welwyn high quality resistors! Surly the capacitors can be upgraded Elna Silmic or so.
I have the Sanken (original) and those driver, I want to give a try.
My NCC200 sound far better than the Ebay kit.
Actually still have that kit, need some capacitors at the protection, I took the out.
I can sell it $15 plus shipping a pair if someone interested. I paid $65 on that time plus shipping.
I can provide picture upon interest.
Greetings Gabor
He looked like your kit. If all is good buy. Send a photo to
yuragruzz@gmail.com
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Old 18th March 2011, 05:54 AM   #624
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Quote:
Originally Posted by Bengali View Post
Hi,

is there much of a difference betweenthe avondale pcb's and the gigaworks kit?

does the gigaworks np140 kit stock kit sound good or requires lot of component replacement or modification. are they using fake transistors(?)

thanks.
I have not changed anything. These transistors in my kit.
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Old 12th April 2011, 02:43 AM   #625
ptempel is offline ptempel  United States
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Was comparing the H-140 with the NCC200 and thought of doing the following mods:

1) Add the two 100nF/0.1uF 50V poly caps that are missing in parallel with the two 100uF elec caps under the board.
2) Add the missing 15 ohm 2W output resistor. Wire in series with speaker binding post cable.
3) Replace the 3K ohm resistor for 2.7K.
4) Replace the BC550 transistors for BC546.
5) Replace the 56pF cap with 47pF mica.
6) Replace the 68uF cap with 68uF mica.
7) Replace the 220pF caps with 220pF polystyrene.
8) Replace the 470pF caps with 470pF polystyrene.
9) Replace the C2240 with ZTX653.
10) Replace the A1145 with ZTX753.
11) Replace ? uF cap with 47uF wet tant.
12) Add 1K ohm resistor between 47uF wet tant and BC546. Have to cut a track and add under the board.
13) Replace TIP41 with MJE15030 NPN.
14) Replace TIP42 with MJE15031 PNP.
15) Replace 2SC5200 with MJ15003.

Which do you think are worth doing? Which ones did you do?

Thanks,
Philippe
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Old 4th May 2011, 07:55 PM   #626
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Location: Cornwall, UK
Hi, Hopefully you can help me

I bought some preassembled NAP140C boards from eB*y (They are blue with Sanken 3858 outputs) And 2 power supply boards with 35a rectifiers & 4 10000uf "Nover" caps... I'm sure you know the ones...Also a pair of 300va 25v transformers.

Wired it all up today and it fired up fine with -70mv dc offset & set the bias at 5mv. connected a pair of speakers & sound lasts for around 3-4 seconds before cutting out, dead. Noticed the green led's on the power supply boards fade out just before it dies. I have found that removing the speaker return wires from ground stops the problem but thats hardly helpful

Tried all different grounding schemes & nothing seems to work so I'm here for any ideas what might be at fault.

Many thanks. PS. the wiring diagram I followed is attached.
Attached Images
File Type: jpg 140cgndschmweb.jpg (90.6 KB, 767 views)
File Type: jpg $(KGrHqMOKowE1z-YTje1BNnHIzi7yQ~~_3.JPG (77.0 KB, 738 views)
File Type: jpg zgpowersupply-2.jpg (65.0 KB, 730 views)

Last edited by istari knight; 4th May 2011 at 08:01 PM.
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Old 5th May 2011, 01:18 AM   #627
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Hi istari knight,

How big is your heatsink?

I would recommend fuses between PSU and the amp, at least for testing.

Test one amp at the time with cheap a speaker or dummy load.

regards
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Old 5th May 2011, 08:07 PM   #628
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Location: Cornwall, UK
Hi, thanks for the reply!

The heatsinks are from 100wpc plate amps & are sufficiant I think.

As I bought the preassembled boards please can you take a look at the above picture of the boards & confirm everything is right ? (Q5 etc)

Many thanks
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Old 6th May 2011, 06:23 AM   #629
2Bak is offline 2Bak  Denmark
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Did you try running separate power grounds from each PSU-board to each amp board....?
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Old 6th May 2011, 06:16 PM   #630
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Quote:
Originally Posted by 2Bak View Post
Did you try running separate power grounds from each PSU-board to each amp board....?
Yep, I tried that first but no different... I'm going to rewire the ground cables now anyway & see what happens - Im sure its a grounding issue of some sort

Is this the board that you have to wire a "jumper" between SG & GND ?

Best regards.
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